The rapper and his wife stepped into an elevator with her singer sibling before she snapped and started to kick out, unleashing a violent attack which was captured by elevator surveillance cameras.

In the video obtained by gossip website TMZ, a man - seemingly a bodyguard - had to step in and hold Solange back after she assaulted her sister's husband.

It is unclear what caused the argument as there is no sound on the black and white surveillance video which was shot after the group attended an after-party at the Boom Boom Room at New York's Standard Hotel.

The man who stepped in to stop the assault is seen hitting the emergency stop switch in the lift - which stopped the fight spilling out.

As the trio exited the building, Solange still looked angry as she got into a car with Beyonce, although the Drunk In Love singer's husband was seen walking to a separate vehicle.

We've no idea what could have triggered the outburst, particularly when the trio looked to be getting on fine when the sisters joined forces as Coachella last month.